The present invention is directed generally to molding presses used for applying a coating of plastic material on the underside of sanitary fixtures such as tubs, sinks, lavatories and the like and, in particular, to a molding press insert table which is placed in the clamp of the press on top of the original lower platen to enable the molding of smaller sanitary fixtures such as sinks, lavatories and the like.
Recently, porcelain cast-iron bathtubs and smaller sanitary fixtures such as sinks have been replaced with composite enamel steel structures of substantially less weight than the prior fixtures but having the look and feel of such earlier fixtures. The composite structures are lighter, have a high structural strength and resist cracking and delamination when subjected to impact, thermal shock or the weight of a user.
A disclosure of such composite structures is found in commonly assigned U.S. Pat. No. 4,664,982. This patent discloses sanitary fixtures having the look and feel of early porcelain cast-iron fixtures. The composite enamel steel fixture is formed from a steel shell, the top surface of which may be coated with enamel and the underside or non-finish surface thereof being coated with a layer of plastic material through reaction injection molding (RIM) or by reinforced reaction injection molding (RRIM) techniques. Other disclosures of such improved sanitary fixtures may be found in commonly assigned U.S. Pat. Nos. 4,664,092, 4,844,944 and 4,844,955.
Typically, in manufacturing such composite molded large sanitary fixtures such as tubs, a shell having a finish and a non-finish side is inserted into a female mold receptacle forming a cavity between the molding receptacle surface and the non-finish portion of the shell. The platen on which the female mold is placed is generally at floor level, with the operative components of the press including the mix head system and ejector system being found below floor level. A male molding portion is supported on an upper moveable platen and includes a surface which substantially conforms to the finish surface contour of the shell. The upper platen is urged downwardly against the finish side of the shell to hold the shell in the female mold portion. The desired polymeric material is injected from the mix head through a bushing into the mold to coat the non-finish side of the shell. The upper platen is then moved away thereby releasing the male mold member from the shell to permit removal of the shell from the female mold portion.
While such larger presses having the platen at floor level are acceptable for use in molding large sanitary fixtures such as tubs, such large molding presses cannot be used to mold smaller sanitary fixtures such as sinks, lavatories or the like because the top platen will not move close enough to the bottom platen to hold the shell in place. This is known as "daylight". In the past, to overcome this "daylight" problem when smaller molds are used, an appropriate spacer was placed on the top platen thereby permitting the male mold portion supported on the top platen to travel farther down. Such modification of the top platen has proven less than completely satisfactory in actual manufacturing situations.
Accordingly, it is desired to provide a manufacturing insert for a molding press which is supported on the original bottom platen of the press to permit the use of smaller molds for molding smaller sanitary fixtures.